Dual fuel system

ABSTRACT

A fuel system for a spark ignited internal combustion engine which feeds gasoline and a volatile gasoline fraction to the engine has a volatile fuel generation means with an appropriate valve switching system designed to allow operation of the engine on the volatile fuel during start and warm-up and then switch to normal fuel during warmed-up operation. The self-generation system utilizes engine vacuum as an aid in vaporizing a portion of the normal gasoline.

United States Patent 1191 Brarnfitt DUAL FUEL SYSTEM [75] Inventor:Thomas Hugh Bramfitt, Pasadena, Tex.

[73] Assignee: Ethyl Corporation, Richmond, Va.

[22] Filed: Nov. 5, 1971 [21] Appl. No.: 195,949

[521 US. Cl 123/127, 123/133, 123/179 G [51] Int. Cl. F02m 13/06 [58]Field of Search 123/2, 3, 179 G,

[56] References Cited UNITED STATES PATENTS 1,744,953 l/l930 Dienner123/127 l/l9l3 Krayer l23/l34 1 Jan. 8, 1974 1,576,766 3/1926 Kloepper123/127 3,021,681 2 1962 Perry 123/133 1,559,214 10/1925 Woolson 123/127Primary ExaminerLaurence M. Goodridge Attorney-Donald L. Johnson, JackF. Sieberth & James M. Pelton [57 7 ABSTRACT A fuel system for a sparkignited internal combustion engine which feeds gasoline and a volatilegasoline fraction to the engine has a volatile fuel generation meanswith an appropriate valve switching system designed to allow operationof the engine on the volatile fuel during start and warm-up and thenswitch to normal fuel during warmed-up operation. The selfgenerationsystem utilizes engine vacuum as an aid in vaporizing a portion of thenormal gasoline.

3 Claims, 5 Drawing Figures PATENTED JAN 8 I974 SHEET 1 OF 2 FIGURE 1INTER LOCKED D ACTUATED SOLENOI VALVES FIGURE 2 UEL INDUCTION NS ENGINEVACUUM LIOUID 'TOF RATOR MEA VAPORIZING VAPOR MEANS SEPA TO GAS TO FUELINDUCTION TA MEANS FIGURE 3 PATENTED 8M4 3.783.849

sum .2 0F 2 /49A 498 To L *ENGINE VACUUM TO "'CARBURETOR FIGURE 4 FIGURE5 DUAL FUEL SYSTEM BACKGROUND OF THE INVENTION The exhaust gas ofinternal combustion engines contains various amounts of unburnedhydrocarbons, carbon monoxide, and nitrogen oxides (NO,). Emission ofthese materials to the atmosphere is undesirable. The problem is moreacute in urban areas having a high concentration of motor vehicles.

During recent years, researchers have investigated extensively means ofreducing exhaust emission. This research has been quite fruitful. As aresult, presentday automobiles emit but a fraction of undesirablematerials compared to those of less than a decade ago.

. These improved results have come about through such means as improvedcarburetion, ignition timing modifications, exhaust recycle, exhaustmanifold air injection, use of lean air/fuel ratios, positive crankcaseventilation, and the like.

Despite the tremendous advances that have been made, furtherimprovements are desirable. Federal standards by 1975 are expected torequire reduction of emissions to only about percent of the level of1970. A major obstacle in achieving further reduction in exhaustemissions is the fact that the engine requires a richer air/fuel mixtureduring start and warm-up. During this period exhaust emissions of eventhe lowest emitting engine is appreciably increased. In the case ofcarburetor induction engines, the required richer Iair/fu'el mixture isusually attained by placing a choke valve in the air passage above thecarburetor venturi, which serves to restrict air flow. In most, but notall, gasolinepowered vehicles the choke is automatically controlled byengine temperature. As soon as the engine reaches an adequate operatingtemperature (i.e., a temperature at which it can operate smoothlywithout choking), the

choke opens. In normal operation this takes about 2-3 minutes. 7 i

In the past, attempts have been made to eliminate the need for this richoperating warm-up period by operating the engine on liquid petroleum gas(LPG) during the warm-up period and switching to gasoline afteroperating temperature is attained. A drawback of this system is that itrequires the vehicle operator to obtain two different kinds offuel-gasoline and LPG. Of even greater consequence is the fact that theuse of a liquid an a gaseous fuel requires a separate metering systemfor each fuel. For example, the LPG fuel system is separate from thegasoline fuel system and provides LPG vaporization, pressure regulation,and finally, vapor induction into the intake air stream through aseparate metering jet. Because of this, the system using LPG fuel isconsidered impractical.

An object of the present invention is to provide a fuel induction systemthat results in lower exhaust emissions. A further object is to providea fuel induction system that allows an engine to start and warm-upwithout the necessity of operating'the engine at a rich air/fuel ratio.A still further object of the invention is to pro-. vide a novel liquidfuel system with self-generation of the more volatile liquid fuel fromthe normal gasoline fuel, thus eliminating the necessity of the vehicleoperator obtaining two separate fuels. Another object is to provide amethod of'operating a gasoline engine in a manner that will result inreduced exhaust emissions.

SUMMARY OF THE INVENTION The present invention in its broadest aspectrelates to a novel fuel system for a spark ignited internal combustionengine (hereinafter simply referred to as an engine) with aself-generation system for producing a liquid hydrocarbon fuel of thelower gasoline boiling range referred to hereafter as a volatilegasoline fraction and the method of accomplishing the generation of thevolatile gasoline fraction in the engine fuel system. Therefore, thisinvention provides in a novel fuel system a vacuum line connected toasource of engine vacuum, vaporizing means in communication with saidvacuum line whereby a portion of the liquid hydrocarbon fuel of thegasoline boiling range, referred to'hereafter as gasoline, is vaporized,vapor-liquid separator means connected to said vaporizing means wherebythe vapor produced in said vaporizing means is separated from theresidual liquid fuel which is depleted in volatile components, and avolatile fuel conduit for delivery of said vapor to the fuel inductionmeans of said engine for operating during a selected period of start andwarm-up. In a preferred aspect of the invention a heater is used to aidvaporization. In another preferred aspect the vaporizing means isresponsive to a pressure difference caused by opening a valve in thevacuum line and causing reduced pressure to develop in the vaporizingmeans. When the pressure difference attains a predetermined level,gasoline from the tank is drawn into the vaporizing means and a portionthereof is volatilized. In another preferred aspect of the inventioncondensing means are connected to the vaporizing means whereby the vaporis substantially completely condensed to form a liquid volatile gasolinefraction or condensate." In a further preferred aspect of the invention,a vacuum chamber having a lower section and an upper section isconnected to the condensing means whereby the condensate is collected inthe lower section and pumped through a one-way check valve to a volatilefuel storage tank; and the upper section is connected to the source ofengine vacuum and maintained under substantially reduced pressure duringoperation of the volatile fuel generation system.

Another broad aspect of this invention is the method of operating anengine having a fuel system which feeds gasoline and a volatile gasolinefraction to said engine, the improvement comprising using engine vacuumto vaporize a portion of gasoline and separating the vapor from theresidual liquid thereby producing a volatile gasoline fraction for.operating said engine during a selected period. In another preferredaspect of this invention, the vapor is condensed forming condensatewhich is stored in a volatile fuel storage container for delivery to thefuel induction means during start and warm-up.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of the basic dualliquid fuel system showing a reservoir for both volatile fuel and normalgasoline and conduits for delivering either through a switching valve tothe fuel bowl of the carburetor. Also shown is a carburetor drainconduit having a valve which allows the carburetor to drain when theengine is turned off.

FIG. 2 is a cross-section of a carburetor having separate fuel bowls forthe normal gasoline and the volatile fuel and interlocked valves forswitching from one fuel to the other. The drawing shows the valvesfunctioning to permit delivery of the fuel from the volatile fuel bowlsuch as would occur during start and warm-up.

FIG. 3 is a schematic representation of the selfgeneration system forproducing the volatile fuel in broad conceptual aspects showing a fuelline leading into a vaporizer which is connected to a vapor-liquidseparator having a vacuum line, volatile fuel line, and residual fuelline.

FIG. 4 is a schematic of the dual fuel systems volatile fuelself-generation system including a vaporizing means, a vapor-liquidseparator having a condenser for the volatile fuel and a vacuum chamberin which the vapor space is connected to the source of engine vacuum.

FIG. 5 is a schematic of the dual liquid fuel system showing theconnection of the volatile fuel selfgeneration system of FIG. 4 to acarburetor on an internal combustion engine. Fuel switching valves areshown for delivery of either volatile fuel or normal gasoline to theengine. Vent lines and pumps are shown.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, apreferred embodiment of the invention is a fuel delivery system for agasoline operated spark ignited internal combustion engine adapted tofeed gasoline and a volatile gasoline fraction to the engine having agasoline tank 1 for gasoline and a container for liquid hydrocarbon fuelof the lower gasoline boiling range 2.

Gasoline is a mixture of hydrocarbons having a boiling range of fromabout 80F to about 430F as measured by ASTM method D-86. Of course,these mixtures can contain individual constituents boiling above orbelow these figures. These hydrocarbon mixtures contain aromatichydrocarbons, saturated hydrocarbons and olefinic hydrocarbons. The bulkof the hydrocarbon mixture is obtained by refining crude petroleum byeither straight distillation or through the use of one of the many knownrefining processes, such as thermal cracking, catalytic cracking,catalytic hydroforming, catalytic reforming, and the like. Generally,the final gasoline is a blend of stocks obtained from several refineryprocesses. The final blend may also contain hydrocarbons made by otherprocedures such as alkylate made by the reaction of C olefins andbutanes using an acid catalyst, such as sulfuric acid or hydrofluoricacid.

Preferred gasolines are those having a Research Octane Number of atleast 85. A more preferred Research Octane Number is 90 or greater. Itis also preferred to blend the gasoline such that it has a content ofaromatic hydrocarbons ranging from to about 60 volume percent, anolefinic hydrocarbon content ranging from 0 to about 30 volume percent,and a saturate hydrocarbon content ranging from about 40 to volumepercent, based on the whole gasoline.

In order to obtain fuels having properties required by modern automotiveengines, a blending procedure is generally followed by selectingappropriate blending stocks and blending them in suitable proportions.The required octane level is most readily accomplished by employingaromatics (e.g., BTX, catalytic reformate, or the like), alkylate (e.g.,C saturates made by reacting C olefins with isobutane using a HF or I-ISO catalyst), or blends of different types.

The balance of the whole fuel may be made up of other components such asother saturates, olefins, or the like. The olefins are generally formedby using such procedures as thermal cracking, catalytic cracking andpolymerization. Dehydrogenation of paraffins to olefins can supplementthe gaseous olefins occurring in the refinery to produce feed materialfor either polymerization or alkylation processes. The saturatedgasoline components comprise paraffins and napthenes. These saturatesare obtained from (1) virgin gasoline by distillation (straight rungasoline), (2) alkylation processes (alkylates), and (3) isomerizationprocedures (conversion of normal paraffins to branchedchain paraffins ofgreater octane quality). Saturated gasoline components also occur inso-called natural gasoline. In addition to the foregoing, thermallycracked stocks, catalytically cracked stocks and catalytic reformatescontain saturated components.

Utilization of non-hydrocarbon blending stocks or components informulating the fuels used in this invention is feasible and, in someinstances, may actually be desirable. Thus, use may be made of methanol,tertiary butanol and other inexpensive, abundant and nondeleteriousoxygen-containing fuel components.

The normal gasoline may contain any of the other additives normallyemployed to give fuels of improved quality, such as tetraalkylleadantiknocks including tetramethyllead, tetraethyllead, mixedtetraethyltetramethyllead, and the like. They may also contain antiknockquantities of other agents such as cyclopentadienyl nickel nitrosyl,methylcyclopentadienyl manganese tricarbonyl, and N-methyl aniline, andthe like. Antiknock promoters such as tert-butyl acetate may beincluded. Halohydrocarbon scavengers such as ethylene dichloride,ethylene dibromide and dibromo butane may be added.Phosphorus-containing additives such as tricresyl phosphate, methyldiphenyl phosphate, diphenyl methyl phosphate, trimethyl phosphate, andtris(,8- chloropropyl)phosphate may be present. Antioxidants such as2,6-di-tert-butylphenol, 2,6-di-tert butyl-pcresol, phenylenediaminess'uch as N- iospropylphenylenediamine, and the like, may be present.Likewise, thegasoline can contain dyes, metal deactivators, or any ofthe additives recognized to serve some useful purpose in improving thegasoline quality.

The liquid hydrocarbon fuel of the lower gasoline boiling range,referred to as a volatile gasoline fraction, is a hydrocarbon having afinal boiling point below that of normal gasoline. In the presentinvention it is not necessary to place an exact value on this finalboiling point and, in fact, it can vary when the novel fuel system isused with different engines. The requirement is that the volatile fu'elhave a final boiling point low enough such that the particular engine towhich the novel fuel system is connected will start and operate smoothlyduring warm-up without resorting to a richer air/fuel ratio than isrequired for operation at normal operating temperature. This is not tosay that the use p of a richer air/fuel ratio is excluded because undervery cold conditions a slightly richer mixture may be required,especially to start the engine. This richer mixture is readily furnishedby such means as choking the engine. However, the amount of time thatthe enriched air/fuel ratio is used will be substantially less than required without the novel fuel system of this invention; and accordingly,even when some choking is required, the overall exhaust emissions willbe still greatly reduced by the use of the novel fuel system of thisinvention.

The optimum final boiling point for the volatile gasoline fraction to beused in the novel fuel system on a particular engine is best determinedexperimentally taking into account the conditions such as temperatureand humidity, etc., under which the engine will be operated. A usefulboiling range for the volatile gasoline fraction is from about 60-300F.Especially good results are obtained in most applications using avolatile fraction having a normal boiling range of from about 70-150F(ASTM D-86). The most preferred volatile fuel is made up of the lightends (low boilers) obtained from normal gasoline. ln fact, embodimentsof this invention, to be described in detail hereafter, include in thenovel liquid fuel system means for removing the light ends from normalgasoline and using these as the volatile gasoline fraction during startand warm-up.

Referring again to FIG. 1, the dual fuel system includes a liquid fuelconduit 3 connecting gasoline tank 1 through fuel selector valve 4 tofuel pump 5 which connects to fuel bowl 6 of carburetor 7. Thecarburetor shown is a single venturi type but the fuel system is equallyapplicable to multiple venturi carburetors such as those having two,three, or four venturi.

Volatile fuel tank 2 is connected by volatile liquid fuel conduit 8 tofuel selector valve 4 which connects through fuel pump 5 to fuel bowl 6of carburetor 7. As

shown in FIG. 1, fuel selector valve 4 is set to deliver normal gasolinefrom gasoline tank 1 to carburetor 7. By revolving the selector valvecounter-clockwise, as shown by the arrow, fuel selector valve 4 willfunction to deliver volatile fuel from volatile fuel tank 2 tocarburetor 7.

Fuel bowl 6 has a fuel drain 9 which can drain residual fuel from thebowl 6 through drain conduit 10 to gasoline tank 1. Drain valve 11 indrain conduit 10 is shown closed and is opened when it is desired todrain '7 fuel bowl 6.

In operation, the embodiment shown in H6. 1 functions as follows.Starting with a cold engine, fuel selector switch 4 is set to open theflow path from volatile fuel tank 2 through fuel pump 5 to fuel bowl 6.Fuel selector valve 4 may be set manually, but is preferably positionedautomatically in response to engine temperature. A temperatureresponsive bimetal switch can be used to signal valve actuating means toset fuel selector valve 4 to supply the proper fuel to fuel bowl 6depending upon a predetermined engine temperature. The bimetal switchcan be positioned to respond to engine temperature at any of severallocations such as carburetor temperature, coolant temperature, oiltemperature, or multiple bimetal switches can be used to respond totemperature at more than one location, thus requiring more than onelocation to attain a predetermined operating temperature before thecircuit is com- 6 pleted to signal the valve actuating means to switchfuel selector valve 4 from one fuel to another. The predeterminedtemperature should be such that when the selector valve 4 is signalledto switch from delivering fuel from volatile fuel tank 2 to normalgasoline tank 1 the engine will operate smoothly with little, orpreferably no, enrichment in the air/fuel ratio by means such aschoking. This operating temperature need not be the final normaloperating temperature of the engine but, rather, an intermediatetemperature somewhere between the coldengine and the final normaloperating temperature. The operating temperature at which selector valve4 switches from volatile fuel to normal gasoline approximates the sametemperature at which the well-known automatic choking in a conventionalfuel system would be open because, in essence, the delivery of thevolatile fuel replaces, or substantially replaces, the use of the choke.

When the engine starter is engaged, fuel pump 5 fills fuel bowl 6 withvolatile fuel. This is delivered through fuel nozzle 12 to carburetorventuri 13 where it is mixed with air and inducted into the engine. Bythe use of the present fuel system, nozzle 12 delivers fuel at a leanerair/fuel ratio than would otherwise be required to start the engineusing normal gasoline. For example, the engine can be started atair/fuel ratios of about 13-1711 whereas conventional systems require amuch richer ratio. Under very adverse conditions, such as very lowtemperature, only minimal enrichment may be required to allow the engineto start and operate smoothly during warm-up.

When the engine reaches an operating temperature at which it can operatesmoothly on normal gasoline with little or no choking, selector valve 4is switched such that it closes the path from volatile fuel tank 2 andopens the path from normal gasoline tank 1 such that fuel bowl 6 issupplied with normal gasoline. As mentioned above, this can beaccomplished manually but is preferably accomplished automatically inresponse to engine temperature.

After the engine has operated using normal gasoline and is turned offfuel bowl 6 will contain residual normal gasoline. Once the engine coolsit will not start and run smoothly of this residual normal gasolinewithout some enrichment of the air/fuel ratio--in other words, somechoking would be required. To avoid this, fuel bowl 6 is preferablydrained after each use so that on the next start-up the initial fuelsupplied to the carburetor will be volatile fuel. This is accomplishedby opening drain valve 11 allowing the residual normal gasoline in fuelbowl 6 to drain through drain conduit 10 to normal gasoline tank 1.Optionally, the fuel bowl could drain to some other container providedfor that purpose. Opening of drain valve 11' can be accomplishedmanually but preferably it is made automatic. One method ofaccomplishing this is to provide valve actuating means such as anelectrical solenoid which keep valve 11 closed when the engineelectrical engine system is turned on and open valve 11 when theignition system is turned off. By this means when the engine is againstarted, drain valve 11 will automatically close and either volatilefuel or normal gasoline will be delivered to fuel bowl 6 depending uponengine temperature.

Referring now to FIG. 2, another embodiment of the invention is shown inwhich a dual fuel carburetor 20 is provided which has a fuel bowl fornormal gasoline 21 and a separate fuel bowl for volatile fuel 22.Selection of fuel delivered to carburetor venturi 23 is accomplished byinterlocked valves 24 and 25. The interlocking provides that when onevalve is open the other is closed. As shown, valve 25 is open andvolatile fuel is being delivered to venturi 23 which would be the properselection at engine start-up and warm-up. When the engine attainsoperating temperature, valve .25 is closed and valve 24 opens such thatnormal gasoline is delivered to venturi 23.

In FIG. 2 each of fuel bowls 21 and 22 have individual fuel deliverypassages. In a similar arrangement the carburetor can be modified suchthat only a single fuel delivery passage through a main nozzle isprovided for each venturi. This single nozzle is supplied with fuel fromeither the volatile fuel bowl or the normal gasoline bowl as requiredand the selection of which fuel is delivered to the single nozzle iscontrolled by valves in the fuel passage connecting the individual fuelbowls to the common nozzle. These valves function in a manner similar tovalves 24 and 25.

Referring to FIG. 3, the normal gasoline is taken from the gasoline tank38 by liquid fuel line 31 and enters the vaporizing means 32 where it ispartially vaporized. The vapor and liquid are separated in vapor-liquidseparator 33, which is connected by vapor-liquid line 34 to thevaporizing means 32. The vapor exits from vapor-liquid separator 33 viavolatile fuel line 35, which connects with the fuel induction means (notshown) such as carburetor. The liquid which is depleted in volatile fuelcomponents is discharged from the vaporliquid separator means 33 viavolatile-depleted fuel line 36 and according to automatically ormanually predetermined conditions is either returned to the gasolinetank or delivered to the fuel induction means. The vapor-liquidseparator 33 must operate under such conditions that the volatile fuelproduced is substantially completely condensed. Thus, the vacuum drawnon the volatile fuel self-generating system by means of vacuum line 37connected to the vaporizing means 32 through vapor-liquid separator 33and to the engine is substantially free of vapor avoiding undue richnessof the air/fuel mixture, fuel economy losses, and fuel meteringproblems.

From the foregoing it is readily apparent that a preferred embodiment ofthis invention is a method of separating normal gasoline into a volatilefraction and a portion depleted in volatile components by partiallyvaporizing said gasoline under vacuum, said vacuum being derived fromthe engine vacuum of a spark ignited internal combustion engine. Thevolatile fraction is then separated from the portion depleted involatile components, i.e., the volatile depleted fuel, and the volatilefraction is used during a selected period of engine operation. Tofacilitate the production of the volatile fraction, the gasoline may beheated prior to vaporization. The amount of vacuum should be thatrequired to vaporize from about to about 50 weight percent of the normalgasoline. Operating under varying conditions, such as idle, normalcruising, and acceleration,

engine vacuum can range from about 10 to about 21 inches of mercury ormore depending on the particular engine. While any convenient source ofengie vacuum may be used, for example, the carburetor venturi vacuum orintake manifold vacuum, the latter is preferred. The portion depleted involatile components need not be completely depleted but the separationshould be such that a major portion of the volatile components in normalgasoline are vaporized and separated in the vapor-liquid separator.

It should also be clear that the vapor-liquid separator 33 of FIG. 3 mayinclude a condenser which is slightly efficient, liquefying the volatileportion substantially completely such that a liquid seal is maintainedbetween the engine vacuum source and the vaporizing means. This may beaccomplished, without limiting the invention, by using refrigeration toobtain substantially complete condensation of the vapor. For the amountand composition of volatile fuel produced if from about 10 to about 50weight percent of the normal gasoline, the volatile fuel would condenseat a temperature from about 30 to about 50F. A convenient source ofrefrigeration in an automobile is the air-conditioning system ifavailable. A person of ordinary skill in the art can suggest thenecessary arrangement of means to connect the condenser to theautomobile airconditioning system. Other mechanical refrigerationsystems using either vapor-compression machines havingpositivedisplacement compressors, such as reciprocating, rotary, orcentrifugal compressors, steam jets or continuous or intermittentabsorption systems using, for example, ammonia or lithium bromide as therefrigerant are typical.

The condenser is connected to a vacuum chamber which acts as a collectorfor the condensate. The vacuum chamber has an upper section which isessentially free vacuum, assuming that the condenser has substantiallycompletely liquefied the vapor and a lower section which collects thecondensate. The lower section can be connected to a suitable pump whichadvances the condensate into a volatile fuel storage container. Theupper section is connected by vacuum line to the source of enginevacuum. the volatile fuel generation system is preferably operated whenthe vapor is completely condensed. This prevents the vapor from enteringthe engine vacuum causing fuel metering problems, unnecessarily richengine operation and penalizing fuel economy. However, a smallnon-condensable fraction would not significantly affect operation of theengine.

Referring to FIG. 4, a preferred embodiment of the invention is a systemfor self-generation of a volatile fuel including a liquid fuel conduit42 connected to the gasoline tank 46C and to expansion valve 41 throughpump 44C and heater 40 in heat exchange relationship with conduit 42 andadapted to heat the liquid fuel in conduit 42. Expansion valve 41 isconnected to vaporizing chamber 43 which has vapor conduit 44 connectedto the vapor discharge outlet, volatile-depleted fuel conduit 46connected to the liquid discharge outlet and a vent line 453 in which islocated relief valve 45A. Volatile-depleted fuel line 46 connects togasoline tank 46C through pump 47 and one-way check valve 42C. Pump 47is actuated by liquid-level switch 40C in vaporizing chamber 43,employing actuating means 41C. Located in vapor conduit 44 is one-waycheck valve 45 which maintains flow in one direction only through vaporconduit 44 to the inlet of condenser 48. Condenser 48 can convenientlybe connected to the automobile air-conditioning system (not shown) orany suitable refrigeration means (not shown) to substantially completelycondense the volatile fuel. The outlet of condenser 48 is connected tovacuum chamber 49 which has upper and lower sections. The lower sectionof vacuum chamber 49 is connected to volatile fuel storage tank 40A bymeans of liquid fuel conduit 43C containing pump 41A and one-way checkvalve 42A. The upper section of vacuum chamber 49 communicates with asource of engine vacuum by vacuum line 49A in which is located valve49B. Also, the upper section of vacuum chamber 49 has vent line 46B inwhich is located pressure relief valve 46A and connects with thegasoline tanke 46C or a suitable absorption system (not shown).

The volatile fuel storage container 40A has in addition to liquid fuelconduit 43C from vacuum chamber 49, a liquid-level switch 43A connectedby actuating means 43B to valve 498, liquid fuel conduit 44A in which islocated pressure regulating valve 45C for delivery of volatile fuel tothe carburetor (not shown), and vent line 47B having pressure reliefvalve 47A. The vent line is connected to the gasoline tank 46C or anysuitable absorption system (not shown). If necessary, an auxiliary fuelpump may be inserted in conduit 44A.

In operation the volatile fuel self-generation system of this preferredembodiment produces a volatile fuel from normal gasoline in which normalgasoline from the gasoline tank 46C is fed through liquid fuel line 42by pump 44C to expansion valve 41 and is heated by means of heater 40located in heat exchange relationship with liquid fuel line 42. Theheater 40 may be an electrically operated resistance heating coilwrapped around fuel line 42 or any other suitable means for heating maybe employed. The heater should be adapted to bring the fuel to atemperature high enough to facilitate vaporization when passed throughexpansion valve 41. For best results the temperature should be fromabout 150F to about 275F and preferably from about 175F to about 250F.The amount of fuel vaporized depends both on temperature and pressureand the two are not independent variables. For best vaporization,conditions should be set experimentally for each particular engine.Typical examples of suitable heaters are heat exchangers using hotengine coolant, direct or indirect gas-fired heaters or the like. Theexpansion valve 41 may be a pressure responsive valve allowing passageand partial vaporization of liquid fuel delivered to it in response to apredetermined pressure differential caused by application of enginevacuum and pressure from pump 44C. The pressure level of expansion valve41 should be set at a level to obtain the desired vaporization inrelation to the valve pressure can adapted vacuum. For best results thepressure should not be less than about 30 psig and preferably theexpansion valve should be set for about 60 psig. The vapor-liquidmixture passes into a vaporizing chamber 43 where the vapor is drawninto vapor conduit 44 through one-way check vlve 45 in response to thedecreased ressure caused by the engine vacuum. The liquid separated fromthe vapor and depleted in volatile fuel components is collected anddrained from the vaporizing chamber 43 through volatile-depleted fuelline 46, and pump 47 responding to liquid-level switch 40C, pumps thevolatile depleted fuel from vaporizing chamber 43 into the gasoline tank46C through one-way check valve 42C by means of conduit 46.Volatiledepleted fuel line 46 can be adapted to return thevolatile-depleted fuel to the gasoline tank 46C or with appropriatevalving cna be adjusted to deliver fuel to the carburetor or separatestorage.

The vapor in vapor conduit 44 is delivered to the condener 48 adapted tosubstantially completely condense the vapor thus producing the volatilefuel. The complete condensation prevents the vapor from entering thevacuum source, which is the engine vacuum, upsetting fuel/air mixturesand lowering fuel economy. As described above, a preferred embodiment ofthe condenser 48 is a refrigeration unit such as those used for anautomotive air-conditioning unit. The condensate is conducted intovacuum chamber 48 where the liquid volatile fuel is collected in thelower section for delivery by liquid volatile fuel conduit 43C to thevolatile fuel storage tank 40A by means of pump 41A through one-waycheck valve 42A. The pump 41A can conveniently be controlled by aconventional liquidlevel controller (not shown) which is connectedthrough the side wall of vacuum chamber 49. The

upper section of vacuum chamber 49 is maintained under vacuum by meansof vacuum line 49A when vacuum valve 498 is in the open position andengine vacuum is drawn on the system.

The opening or closing of vacuum valve 49B is controlled by theliquid-level switch 43A in volatile fuel storage tank 40A and signalsthe vacuum valve 49B through actuating means 438. When the amount ofliquid volatile fuel falls below a predetermined level, the switch 43Asignals vacuum valve 498 via actuating means 43B, the valve is openedand engine vacuun is drawn on the system causing vaporization of thenormal gasoline to produce more volatile fuel. The liquid level involatile fuel storage tank 40A should be high enough to allow sufficientvolatile fuel for cold start and warm-up operations.

From the volatile fuel storage tank 40A the liquid volatile fuel isdelivered to the engine fuel induction means (not shown), such as aconventional carburetor, by liquid fuel conduit 44A. Valve 45C passesthe liquid volatile fuel from the volatile. fuel storage tank by conduit44A to the carburetor. A valve switching arrangement as described inFIG. 5, but not shown here, determines when volatile fuel is deliveredto the carburetor.

For safety purposes relief valves 45A, 46A, and 47A are located in ventlines 45B, 46B, and 47B, respectively, which are attached to thevaporizing chamber 43, vacuum chamber 49, and volatile fuel storage tank40A, respectively. The vent lines can be connected to the gasoline tank46C or any other suitable vapor absorption system used on theautomobile.

From the foregoing description of FIG. 4, it can be seen that apreferred embodiment of this invention is in a fuel system which feedsgasoline and a volatile gasoline fraction to a spark ignited internalcombustion engine during selected periods of engine operation, theimprovement comprising a. a vacuum line connected at one end to a sourceof engine vacuum, b. a vaporizing chamber connected by a liquid fuelline to a gasoline tank, 0. a vacuum chamber connected to the other endof said vacuum line, and a vapor conduit connecting said vaporizingchamber with said vacuum chamber. In another more preferred embodimentof the above fuel system, the

vaporizing chamber is pressure responsive whereby a portion of saidgasoline delivered to said chamber through said liquid fuel line isvaporized in response to a predetermined pressure drop from said liquidfuel line to said vaporizing chamber caused by said engine vacuum.Another more preferred embodiment of the above fuel system has heatingmeans in heat exchange relationship with said liquid fuel line wherebysaid gasoline is heated prior to entering said vaporizing chamber.Another preferred embodiment of this invention has a condensing means insaid vapor conduit whereby the vapor produced from said gasoline in saidvaporizing chamber is substantially completely condensed, producing aliquid volatile gasoline fraction. In another preferred embodiment thevacuum chamber comprises a lower section for collecting the condensateand an upper section communicating with said engine vacuum source bysaid vacuum line whereby the upper section of said vacuum chamber ismaintained under vacuum during'operation of said fuel system to producesaid volatile gasoline fraction. A most preferred embodiment has in thevacuum chamber a pervious vapor-liquid impingement separator meanswhereby said condensate is separated from any uncondensed vapor. Inanother most preferred embodiment of this invention the fuel system hasa. a heater in heat exchange relationship with said liquid fuel linewhereby said gasoline is heated prior to entering said vaporizingchamber thereby facilitating vaporization,

b. a pressureresponsive valve means connected to said liquid fuel lineand downstream of said heater, whereby a portion of said gasoline isvaporized in response to a predetermined pressure drop across said valvefrom the upstream side of said valve to the downstream side of saidvalve caused by said engine vacuum, and

c. a volatile fuel storage tank having an inlet connected to said vacuumchamber through pump means and one-way check valve means, an outletconnected by a liquid volatile fuel conduit to the fuel induction meansof said engine, pressure relief valve means adapted to open on reachinga predetermined pressure, and pressure regulating valve means in saidliquid volatile fuel conduit adapted to deliver liquid volatile fuel tosaid fuel induction means at a preset pressure.

Referring to FIG. 5, a preferred embodiment of the invention is shown inwhich the volatile fuel selfgeneration system of FIG. 4 is connected toa spark ignited internal combustion engine. FIG. 5 shows a normalgasoline tank 50 connected to the volatile fuel selfgeneration systemand also directly to the engine. A fuel switching arrangement isprovided to alternately deliver the normal gasoline or the volatilegasoline fraction to the fuel induction means, for example a carburetor,during selected periods of engine operation. The normal gasoline tank 50is connected to fuel inlet 52 of the carburetor by liquid fuel conduit51 in which is located fuel pump 53 and fuel selector valve 54. A secondliquid fuel conduit 55, connected to line 51 between pump 52 and valve54, connects gasoline tank 50 through heater 59C and expansion valve 56to vaporizing chamber 57. Vaporizing chamber 57 is connected through itstop end closure by vapor conduit 58 through one-way check valve 59 tothe inlet of condenser 50A. The outlet of condenser 50A connects tovacuum chamber 51A through volatile fuel conduit 503. Vacuum chamber 51Aconnects through its top end closure to the engine intake manifold 52Aby means of vacuum conduit 54A in which valve 55A is located. In theevent that the vapor is not completely condensed in condenser 50A,vacuum chamber 51A can also contain a vapor-liquid impingement separatorto completely separate the liquid volatile fuel from said vapor. The useof a vapor-liquid separator would prevent the vapor from carryingentrained liquid volatile fuel with it into the engine vacuum. Vacuumchamber 51A is also connected through its bottom end closure by liquidvolatile fuel conduit 53D to volatile fuel storage tank56A through pump57A and one-way check valve 58A. The bottom of volatile fuel storagetank 56A is connected by volatile fuel conduit 59A through fuel selectorvalve 528 to the fuel inlet 52 of the carburetor. Located in conduit 59Ais pump 513. The top of volatile fuel storage tank 56A is connectedthrough pressure relief valve 538 by a second vapor conduit 54B backtothe gasoline tank 50.

The vacuum chamber 51A is also connected through its top end closure bya vapor 558 through pressure relief valve 568 to the gasoline tank 50.Vaporizing chamber 57 is connected through its top end closure togasoline tank 50 by a vapor conduit 578 having pressure relief valve58B.

Vaporizing chamber 57 connects through its bottom end to the gasolinetank 50 through volatile-depleted fuel conduit 598 having locatedtherein pump 52D and one-way check valve 50C. Located in vaporizingchamber 57 is liquid-level switch 51C which is connected to pump 52D byactuating means 51D and is adapted to close volatile-depleted fuel line59B.

Drain conduit 52C connects a drain outlet at the bottom of thecarburetor fuel bowl such as drain 9 in FIG. 2 through valve 53C to fuelconduit 51 between gasoline tank 50 and fuel pump 53.

Bimetal thermal switch 54C is connected by actuating means 55C and 56Cto valves 52B and 54 respectively.

Located inside volatile fuel storage tank 56A is liquid-level switch 57Cwhich connects through the side wall of tank 56A by actuating means 58Cto a valve 55A.

In operation starting with a cold engine turning the igntiion on causesdrain valve 53C to close. Thermal switch 54C responding to the lowengine temperature has valve 52B in an open position and valve 54 in aclosed position. Volatile gasoline fraction from volatile fuel storagetank 56A is delivered through conduit 59A by pressure regulating valve518 in response to conventional signalling means, such as by a standardfloat actuated fuel bowl valve and fills the fuel bowl of thecarburetor. Actuating the starter starts the engine which operateswithout choking using the volatile gasoline fraction.

After 2 to 3 minutes of operation the liquid engine coolant temperaturerises to a predetermined level at which experience has shown theparticular engine can operate on normal gasoline without choking.Thermal switch 45C senses this temperature and actuates valve 528 toclose and valve 54 to open. During continued operation, normal gasolineis supplied to the carburetor from gasoline tank 50 through fuel conduit51.

Assuming the liquid level in volatile fuel storage tank 56A has droppedbelow a predetermined level (which level should provide sufficientreserve volatile fuel to start and warm-up the engine), liquid-levelactuated switch 57C closes and by actuating means 58C opens valve 55A. Avacuum from the engine manifold 52A is drawn on the volatile fuelgeneration system which operates in the manner described in FIG. 4.

Therefore, it can be seen that without limiting the invention, theforegoing description provides a preferred embodiment of another aspectof the invention which is in a fuel system for feeding gasoline and avolatile gasoline fraction to a spark ignited intneral combustionengine, comprising means for delivering gasoline to the fuel inductionmeans, means for delivering a volatile gasoline fraction to said fuelinduction means, fuel switching means adapted to deliver said volatilegasoline fraction to said fuel induction means during a selected periodof engine operation, and self-generation means for producing saidvolatile gasoline fraction by vaporizing a portion of said gasoline in avaporizing chamber, separating the .vapor and condensing said vapor toform said volatile gasoline fraction, the improvement comprising enginevacuum means connected by a vacuum conduit to said self-generationmeans, vacuum valve means connected in said vacuum conduit between saidvacuum means and said selfgeneration means, and means to signal saidvacuum valve means to open causing a reduction in pressure in saidvaporizing chamber of said self-generation means to produce saidvolatile gasoline fraction and to close causing the production of saidvolatile gasoline fraction to cease.

In a most preferred embodiment of the above fuel system the vacuum meansis the engine intake manifold of said engine. In another preferredembodiment of the invention is the fuel system above having in saidselfgeneration menas a container for said volatile gasoline fractionconnected by a volatile liquid fuel conduit to said fuel inductionmeans. A still further preferred embodiment of the invention is the fuelsystem above wherein said vacuum valve means is controlled by aliquid-level sensing means in said container for said volatile gasolinefraction whereby at a liquid level below a predetermined level saidliquid-level sensing means causes said vacuum valve to open which causesa reduction in pressure in said vaporizing chamber resulting in thevaporization of a portion of said gasoline producing said volatilegasoline fraction and at a liquid level above a predetermined level saidliquid-level sensing means causes said vacuum valve to close whichcauses the production of said volatile gasoline fraction to cease.

I claim:

1. In a fuel system which feeds gasoline and a volatile gasolinefraction to a spark ignited internal combustion engine during selectedperiods of engine operation, the improvement comprising a vacuum lineconnected at one end to a source of engine vacuum, a vaporizing chamberconnected by a liquid fuel line to a gasoline tank, a vacuum chamberconnected to the other end of said vacuum line, said vacuum chambercomprising a lower section for collecting the condensate and an uppersection communicating with said engine vacuum source by said vacuum linewhereby the upper section duced from said gasoline in said vaporizingchamber is substantially completely condensed, producing a liquidvolatile gasoline fraction, a heater in heat exchange relationship withsaid liquid fuel line whereby said gasoline isheated prior to enteringsaid vaporizing chamber thereby facilitating vaporization, a pressureresponsive valve mans connected to said liquid fuel line and downstreamof said heater, whereby a portion of said gasoline is vaporized inresponse to a predetermined pressure drop across said valve from theupstream side of said valve to the downstream side of said'valve causedby said engine vacuum, and a volatile fuel storage tank having an inletconnected to said vacuum chamber through pump means and one-way checkvalve means, an outlet connected by a liquid volatile fuel conduit tothe fuel induction means of said engine, pressure relief valve meansadapted to open on reaching a predetermined pressure, and pressureregulating valve means in.

said liquid volatile fuel conduit adapted to deliver liquid volatilefuel to said fuel induction means at a preset pressure.

2. In a fuel system which feeds gasoline and a volatile gasolinefraction to a spark ignited internal combustion engine during selectedperiods of engine operation, the improvement comprising a. a vacuum lineconnected at one end to a source of engine vacuum,

b. a vaporizing chamber connnected by a liquid line to a gasoline tank,

c. a vacuum chamber connected to the other end of said vacuum line,

d. a vapor conduit connecting said vaporizing chamber with said vacuumchamber,

e. a heater in heat exchange relationship with said liquid fuel linewhereby said gasoline is heated prior to entering said vaporizingchamber thereby facilitating vaporization,

f. a pressure responsive valve means connected to said liquid fuel lineand downstream of said heater, whereby a portion of said gasoline isvaporized in repsonse to a predetermined pressure drop across said valveto the downstream side of said valve caused by said engine vacuum, and

g. a volatile fuel storage tank having an inlet connected to said vacuumchamber through pump means and one-way check valve, an outlet connectedby a liquid volatile fuel conduit to the fuel induction means of saidengine, pressure relief valve means adapted toopen on reaching apredetermined pressure, and pressure regulating valve means in saidliquid volatile fuel conduit adapted to deliver liquid volatile fuel tosaid fuel induction means at a preset pressure.

3. In a fuel system which feeds gasoline and a volatil gasoline fractionto a spark ignited internal combustion engine during selected periods ofengine operation, the improvement comprising a. a vacuum line connectedat one end to a source of engine vacuum;

b. a vaporizing chamber connected by a liquid fuel line to a gasolinetank;

c. a vacuum chamber connected to the other end of said vacuum line, saidvacuum chamber comprising a lower section for collecting the condensateand an upper section communicating with said engine vacuum source bysaid vacuum line whereby the upper section of said vacuum chamber ismainfuel the downstream side of said valve caused by said engine vacuum;and

g. a volatile fuel storage tank having an inlet connected to said vacuumchamber through pump means and one-way check valve means, an outletconnected by a liquid volatile fuel conduit to the fuel induction meansof said engine. pressure relief valve means adapted to open on reachinga predetermined pressure, and pressure regulating valve means in saidliquid volatile fuel conduit adapted to deliver liquid volatile fuel tosaid fuel induction means at a preset pressure.

mg UNITED sm ss Parana? orrlcn QERUHCATE @55 @fiBREC'iWN Patent No.5,785,8 l9 Dated, January 8, 197 i Inventor(s) Thomas Hugh Bramfitt Itis certified that error appears in the ebove-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

E301. 6, line 67, reads "fuel carburetor", should read fuel bowlcarburetor Col. '7, line 10, the following paragraph was omitted:

Valves 2 and 25 can be operated manually but are preferably coupled withthe previously-described engine temperature sensing bimetal switch whichwas used. to actuate valve ft in Figure 1. In this manner, valve 2 5will be automatically opned. on start and. warmup. When the engineattains smooth operating temperature, valve 25 will automatically closeand. valve 24 will open. Valves 2 L and 25 are also interlocked. withvalve E in normal .gasoline conduit 21 and valve 28 in volatile fuelconduit 29 such that when valve 25 is open valve 28 is open and valves24 and 26 are closed .fLikeWise, when the engine attains operatingtemperature and. valve 24 opens, valve 26 also opens andv valves 2 5 anda close.

Col. 7, line o l, reads "engie", should read engine Col. 8, line 5,reads "slightly should read. highly Col. 9, line W, delete 'valvepressure can a d ap ted vacuum" and insert engine vacuum. Col. 9, Line.53, reads "vlve should read. valve f Col. 9, line M T-reads "ressure",should read. pressure Col. 9, line 6%, reads "cna be adjusted", shouldread can be adapted. Col. 10, line 8, reads "#8", should read. 49 Col.10, line 60, add "d Col. 11, line 59, reads "pump'52", should read. pump55 Col. 12,

line 19, reads vapor 55B should read vapor conduit 55B Col, 12, line 54,reads "2 should read l Col. 15,

line 52, reads "menas", should read means 9 Col. 15, line 65, reads"sid", should read. said Col, 14, line 7,

reads "man s should read means Col. l t, line +7, reads "valve, an",should read-- valve means, an

Signed and sealed this 19th day of November 1974.

(SEAL) attest:

MecoY M. GIBSON "JR. c MARSHALL DANN Attesting Officer Commissioner ofPatents

1. In a fuel system which feeds gasoline and a volatile gasolinefraction to a spark ignited internal combustion engine during selectedperiods of engine operation, the improvement comprising a vacuum lineconnected at one end to a source of engine vacuum, a vaporizing chamberconnected by a liquid fuel line to a gasoline tank, a vacuum chamberconnected to the other end of said vacuum line, said vacuum chambercomprising a lower section for collecting the condensate and an uppersection communicating with said engine vacuum source by said vacuum linewhereby the upper section of said vacuum chamber is maintained undervacuum during operation of said fuel system to produce said volatilegasoline fraction, said vacuum chamber having a pervious vaporliquidimpingement separator means whereby sid condensate is separated from anyuncondensed vapor, a vapor conduit connecting said vaporizing chamberwith said vacuum chamber, condensing means in said vapor conduit wherebythe vapor produced from said gasoline in said vaporizing chamber issubstantially completely condensed, producing a liquid volatile gasolinefraction, a heater in heat exchange relationship with said liquid fuelline whereby said gasoline is heated prior to entering said vaporizingchamber thereby facilitating vaporization, a pressure responsive valvemans connected to said liquid fuel line and downstream of said heater,whereby a portion of said gasoline is vaporized in response to apredetermined pressure drop across said valve from the upstream side ofsaid valve to the downstream side of said valve caused by said enginevacuum, and a volatile fuel storage tank having an inlet connected tosaid vacuum chamber through pump means and one-way check valve means, anoutlet connected by a liquid volatile fuel conduit to the fuel inductionmeans of said engine, pressure relief valve means adapted to open onreaching a predetermined pressure, and pressure regulating valve meansin said liquid volatile fuel conduit adapted to deliver liquid volatilefuel to said fuel induction means at a preset pressure.
 2. In a fuelsystem which feeds gasoline and a volatile gasoline fraction to a sparkignited internal combustion engine during selected periods of engineoperation, the improvement comprising a. a vacuum line connected at oneend to a source of engine vacuum, b. a vaporizing chamber connnected bya liquid fuel line to a gasoline tank, c. a vacuum chamber connected tothe other end of said vacuum line, d. a vapor conduit connecting saidvaporizing chamber with said vacuum chamber, e. a heater in heatexchange relationship with said liquid fuel line whereby said gasolineis heated prior to entering said vaporizing chamber thereby facilitatingvaporization, f. a pressure responsive valve means connected to saidliquid fuel line and downstream of said heater, whereby a portion ofsaid gasoline is vaporiZed in repsonse to a predetermined pressure dropacross said valve to the downstream side of said valve caused by saidengine vacuum, and g. a volatile fuel storage tank having an inletconnected to said vacuum chamber through pump means and one-way checkvalve, an outlet connected by a liquid volatile fuel conduit to the fuelinduction means of said engine, pressure relief valve means adapted toopen on reaching a predetermined pressure, and pressure regulating valvemeans in said liquid volatile fuel conduit adapted to deliver liquidvolatile fuel to said fuel induction means at a preset pressure.
 3. In afuel system which feeds gasoline and a volatile gasoline fraction to aspark ignited internal combustion engine during selected periods ofengine operation, the improvement comprising a. a vacuum line connectedat one end to a source of engine vacuum; b. a vaporizing chamberconnected by a liquid fuel line to a gasoline tank; c. a vacuum chamberconnected to the other end of said vacuum line, said vacuum chambercomprising a lower section for collecting the condensate and an uppersection communicating with said engine vacuum source by said vacuum linewhereby the upper section of said vacuum chamber is maintained undervacuum during operation of said fuel system to produce said volatilegasoline fraction; d. a vapor conduit connecting said vaporizing chamberwith said vacuum chamber; e. a heater in heat exchange relationship withsaid liquid fuel line whereby said gasoline is heated prior to enteringsaid vaporizing chamber thereby facilitating vaporization; f. a pressureresponsive valve means connected to said liquid fuel line and downstreamof said heater, whereby a portion of said gasoline is vaporized inresponse to a predetermined pressure drop across said valve from theupstream side of said valve to the downstream side of said valve causedby said engine vacuum; and g. a volatile fuel storage tank having aninlet connected to said vacuum chamber through pump means and one-waycheck valve means, an outlet connected by a liquid volatile fuel conduitto the fuel induction means of said engine, pressure relief valve meansadapted to open on reaching a predetermined pressure, and pressureregulating valve means in said liquid volatile fuel conduit adapted todeliver liquid volatile fuel to said fuel induction means at a presetpressure.